It's just what it sounds. You either require more memory, or you can crank down some settings. Maybe also crop-render? Inserting lots of custom-made objects with varied textures also eats up the RAM. The latter is most serious trouble according to my observations.

Silly me - when I viewed the second attachment I actually clicked "OK"!

Indeed, a major memory problem, running out of space. What are your detail settings, including micropoly detail, AA, GI, cloud and atmosphere samples, and soft shadow samples on light(s)?

I also want to mention that if you were customizing the Subdiv Cache sizes in previous versions of Terragen, you should not do so with TG4. We've put that setting into Subdiv Settings, but I think it may remain customized if you load an older project. So if you're rendering something you originally created in TG3 and you customized the subdiv cache size, returning that to auto may help reduce memory use.

I also want to mention that if you were customizing the Subdiv Cache sizes in previous versions of Terragen, you should not do so with TG4.

I agree.

Quote

We've put that setting into Subdiv Settings, but I think it may remain customized if you load an older project. So if you're rendering something you originally created in TG3 and you customized the subdiv cache size, returning that to auto may help reduce memory use.

You don't need to worry about this because it ignores the old setting. The change log says this:

"Settings to control the size of the subdiv cache will not be carried over from previous projects. The renderer now ignores these settings unless "Override size of subdiv cache" is turned on. By default it's off."

Ah, well that explains a bit. Easy Clouds use the new "v3" cloud scattering model which does use more memory than "v2" clouds (all clouds in TG3 were "v2"). The more layers of v3 clouds you use, the more cloud interaction there is, and the higher the memory use and render time.